Betta Fish: Do I need to separate my Betta and Amanos?

I just got my betta and put him in my tank which already housed 4 Amano shrimp. It is a 55 litres(14 gallon) aquascaping tank with lots of plants. The Amanos don‘t seem to appreciate their new friend too much. 2 of them I have not seen in the 4 days since the betta was added. Whenever the betta sees a shrimp, he will approach and stare at it from a very close(almost touching) distance. He does not seem to bite. -But from discomfort the shrimp flicks away, to which the betta follows rapidly until he looses the now hiding shrimp out of sight.

I am unsure what to do. Is this hunting behaviour which there is no chance of having them together(I need to separate them as soon as possible), or should I still give it time and they might get used to each other?